As one doctor wrote at the time, “the spices in it are bad, the vinegar is a seething mass of rottenness.” She called the pickled cucumber “depraved.” Once they were school-aged, as Ziegelman wrote in the New York Times, immigrant children were indoctrinated by the city’s board of education into a blander, more “normal” American diet of creamed fish and applesauce. Today, of course, few people can tell the difference between the descendant of an Eastern European New Yorker and one whose ancestors came on a slightly earlier boat. And even fewer would look twice at a New Yorker eating a pickle.

Irish Catholics and Irish Protestants might also look alike, and—at least to a foreign ear—sound alike. But the Troubles of the late twentieth century, in which the mostly Protestant unionists fought the mostly Catholic nationalists, is further proof, like so many other sectarian clashes, that even small dissimilarities can spark hatred. With tensions running high, the two groups found surprising ways to tell one another apart. One such shibboleth was the letter “h”: Protestants pronounced it “aitch”; Catholics, “haitch.” Paramilitary gunmen were known to force people to say the letter aloud to determine whose side they were on.93

In 1998, the Irish writer Nuala O’Faolain described in an Irish Times article94 how high-stakes this verbal twist could be. “You spell out a word to someone who’s filling in a form and she looks up and smiles: ‘You said haitch instead of aitch,’ she says. ‘You must be Catholic.’ With that, you realize that she must be a Catholic or she wouldn’t have risked the remark.”

The idea that a diverse array of people is okay—or even good—to have around is a rather new concept. In the early 1900s, American state legislatures took it upon themselves to deport “criminals, lunatics, and other social misfits” beyond their borders, writes Peter Schrag in his book Not Fit for Our Society.95 In 1901, Missouri went so far as to forbid the “importation of afflicted, indigent, or vicious children.”

Henry Cabot Lodge, the turn-of-the-twentieth-century senator from Massachusetts, called for reduced immigration on the basis of State Department reports that southern Italians are “generally rustic and of the lowest type of the Italian as to character and intelligence,”96 and that European countries were sending their worst people—“criminals, vicious characters, and paupers”—to97 the U.S. in order to pare down their own charity rolls. “The immigration of people removed from us in race and blood is rapidly increasing,” Lodge98 wrote, and “these people are almost wholly illiterate.” Of course, some Southwestern states want more people, he acknowledged, but they can’t come at the expense of “lowering the standard of American citizenship.”